ARM Cortex-A7 offers a microdot-sized glimpse into the future of mobile processors

Share This article

ARM Holdings is the UK-based company that creates the processor architectures and instruction sets used in today’s mobile devices. ARM recently announced its newest processor, the Cortex-A7, which is a low-power core designed to be used in conjunction with more powerful high-end Cortex-A15 cores. Despite its small scale, the A7 could revolutionize system-on-a-chip (SoC) design going forward.

The Cortex-A7 is built using the same 28nm manufacturing process that will be used in the A15, but the CPU itself is much smaller. In its finished form, each Cortex-A7 is only 0.5mm2, or roughly 700 micrometers across — the size of a microdot, or the width of a few human hairs. It is designed to clock as high as 1.2GHz in single or multi-core configurations, but won’t do as much work per clock cycle as the A15.

The A7 might not have the raw speed of the next-generation Cortex-A15 core, but it sips power by comparison. ARM hopes to see the A7 used in a so-called big.LITTLE arrangement, with A7 as a low-power complement to faster cores. ARM expects most next-generation SoC designs to incorporate a dual-core A15 (big) along with a dual-core A7 array (little).

The minuscule size will allow OEMs to easily integrate the A7 into SoC designs. The A7 core can be used to handle processes when a device is at idle, or when demands are low, leaving the A15 cores to do the heavy lifting. The company has also developed Coherent Interconnect technology to intelligently shuffle bits between the cores based on system needs. ARM believes that the result will be much lower power consumption overall.

If this strategy sounds familiar, there’s a good reason for that. Nvidia recently released details on its new Tegra 3 SoC, previously codenamed Kal-El. Although Tegra 3 uses Cortex-A9 rather than A15, Nvidia has a special low-power Cortex-A9 on the SoC to accomplish much the same task as the new A7 will with A15.

Nvidia was quite happy to tout its patented Companion Core strategy for saving power, but now it looks like other OEMs will have access to similar technology without suffering the in-house development costs. Nvidia is conveniently missing from a list of Cortex-A7 licensees which includes the likes of TI and Samsung.

Cortex-A7 doesn’t just have a future as a helper core to the beefier A15; this processor can hold its own in a moderately-priced device down the line. ARM suggested that a dual-core A7 SoC could power a device of similar capability to today’s high-end phones as early as 2013-2014. This makes it a perfect fit for emerging markets where price sensitivity is of concern. ARM estimates that a Cortex-A7 phone could go for as little as $100 unlocked.

Having a nearly drop-in solution for low-power processing in phones and tablets will be excellent when the parts actually start to ship. It’s possible that Nvidia will continue using its Companion Core system, but other manufacturers may be able to compete without significant engineering challenges. As of now, the expected timeline puts devices with Cortex-A7 in the early 2013 window.

Use of this site is governed by our Terms of Use and Privacy Policy. Copyright 1996-2015 Ziff Davis, LLC.PCMag Digital Group All Rights Reserved. ExtremeTech is a registered trademark of Ziff Davis, LLC. Reproduction in whole or in part in any form or medium without express written permission of Ziff Davis, LLC. is prohibited.